The CVT grouping includes infinitely variable transmissions (IVT) so that give a zero output speed within the operating range.
#CONTINUOUSLY VARIABLE TRANSMISSION RESEARCH PAPER MANUAL#
Contrast with either manual or conventional automatic transmissions that make use of discrete ratios as well as normally disengage when changing ratio. A continuously variable transmission (CVT) transfers power throughout a range of speed/torque ratios from engine input towards output, continuously exclusive of interruption. The suppleness of a CVT allows the input shaft to maintain a constant angular velocity. This contrasts with other mechanical transmissions that offer a set number of gear ratios. motorcycles), a centrifugal clutch is added to facilitate a "neutral" stance, which is useful when idling or manually reversing into a parking space.Ī continuously variable transmission (CVT) is a usual transmission that can change seamlessly through a continuous range of effective gear ratios and CVT also known as a single-speed transmission, stepless transmission, pulley transmission, or, in case of motorcycles, a twist-and-go. A CVT does not strictly require the presence of a clutch. This is typically higher than the RPM that achieves peak efficiency. When power is more important than economy, the ratio of the CVT can be changed to allow the engine to turn at the RPM at which it produces greatest power. A belt-driven design offers approximately 88% efficiency, which, while lower than that of a manual transmission, can be offset by lower production cost and by enabling the engine to run at its most efficient speed for a range of output speeds. The flexibility of a CVT allows the input shaft to maintain a constant angular velocity. This contrasts with other mechanical transmissions that offer a finite number of gear ratios. In comparison with the CVT, the concept is more compatible with present bus technology.A continuously variable transmission (CVT) (also known as a single-speed transmission, stepless transmission, variable pulley transmission, or, in case of motorcycles, a twist-and-go) is an automatic transmission that can change seamlessly through a continuous range of effective gear ratios. The report concludes that such accessory speed control may represent an attractive way to reduce fuel consumption. For this reason, a separate study of accessory speed control has been conducted, yielding a predicted fuel saving of as high as 17 percent. It is shown that a substantial part of this saving arises from the simple fact that the accessories operate at a lower speed.
For the former, assuming an efficiency of 85 percent, a fuel savings of 12 to 22 percent is predicted, depending upon the driving cycle. Computer simulations are made to compute the fuel use of a bus with two different CVTs-one with a ratio range of 6, and the other of an infinite ratio range. The analysis focuses on the use of a CVT alone, without regenerative braking. This computer study and literature survey considers several examples of CVTs in buses, both with and without flywheel energy storage, and finds a predicted energy savings of 10 to 32 percent.
It has been suggested that such transmissions may be of interest for two reasons: (1) simple substitution of a CVT in the place of a conventional transmission may offer fuel savings by allowing the engine to operate at its most efficient speed, and (2) the combination of a CVT and a flywheel allows regenerative braking, in which the vehicle kinetic energy during deceleration is captured for later re-use. This computer study and literature review is intended to provide insight into the potential applicability of CVTs to buses. However, a CVT can provide some fuel economy benefit with or without an energy-storing flywheel, which is the focus of this report. Flywheel systems require a continuously variable transmission (CVT) of some type to transmit power between the flywheel and the drive wheels. Numerous studies have been conducted on the concept of flywheel energy storage for buses.
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